Which step does not involve in DNA finger printing

Options

A. Southern boltting
B. Gel electrophoresis
C. Restriction enzyme digestion
D. Northern blotting

Answer

To determine which step does not involve DNA fingerprinting, we need to analyze the options provided:

1. **Southern Blotting**: This technique is used to transfer DNA from a gel to a membrane and is essential in DNA fingerprinting for analyzing DNA fragments.

2. **Gel Electrophoresis**: This method separates DNA fragments based on their size and is a crucial step in DNA fingerprinting to visualize the DNA profiles.

3. **Restriction Enzyme Digestion**: This process involves cutting DNA into smaller fragments using specific enzymes, which is a fundamental step in preparing DNA samples for fingerprinting.

4. **Northern Blotting**: This technique is specifically used for the transfer and analysis of RNA, not DNA. Since DNA fingerprinting focuses on DNA rather than RNA, this step is not involved in the process.

Based on this analysis, the step that does not involve DNA fingerprinting is **Northern Blotting**.

### Step-by-Step Solution:
1. **Identify the Techniques**: List the techniques provided in the options: Southern Blotting, Gel Electrophoresis, Restriction Enzyme Digestion, Northern Blotting.

2. **Understand Each Technique**:
- Southern Blotting: Used for DNA analysis.
- Gel Electrophoresis: Separates DNA fragments by size.
- Restriction Enzyme Digestion: Cuts DNA into fragments.
- Northern Blotting: Used for RNA analysis.

3. **Determine Relevance to DNA Fingerprinting**: Assess which techniques are relevant to DNA fingerprinting.
- Southern Blotting, Gel Electrophoresis, and Restriction Enzyme Digestion are all relevant.
- Northern Blotting is not relevant as it deals with RNA.

4. **Conclusion**: Conclude that Northern Blotting is the technique that does not involve DNA fingerprinting.

### Final Answer:
The step that does not involve DNA fingerprinting is **Northern Blotting**.